CTest: Use integer-representable value for "infinite" timeout

Refactoring in commit 66419bc046 (CTest: convert timeouts to
std::chrono::duration, 2017-11-20) changed out "infinite" timeout to a
value not representable by a 64-bit integer.  This causes undefined
behavior when e.g. KWSys Process converts the duration to a `long` to
interact with system APIs.  Use the old `1.0e7` maximum value.

Source/CTest/cmCTestScriptHandler.cxx

@@ -1,12 +1,5 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-
-#ifdef _WIN32
-/* windows.h defines min() and max() macros, unless told to otherwise. This
- * interferes with std::min() and std::max() at the very least. */
-#define NOMINMAX
-#endif
-
 #include "cmCTestScriptHandler.h"
 
 #include "cmsys/Directory.hxx"
@@ -970,13 +963,13 @@ bool cmCTestScriptHandler::TryToRemoveBinaryDirectoryOnce(
 std::chrono::duration<double> cmCTestScriptHandler::GetRemainingTimeAllowed()
 {
   if (!this->Makefile) {
-    return std::chrono::duration<double>::max();
+    return cmCTest::MaxDuration();
   }
 
   const char* timelimitS = this->Makefile->GetDefinition("CTEST_TIME_LIMIT");
 
   if (!timelimitS) {
-    return std::chrono::duration<double>::max();
+    return cmCTest::MaxDuration();
   }
 
   auto timelimit = std::chrono::duration<double>(atof(timelimitS));